The present invention pertains to a fluid control system, and, in particular, to a system for controlling oil or other lubricating liquid fluid leakage on a rotating shaft or flywheel in a device such as a mechanical press. The shaft or flywheel may also be subjected to axial movement.
Mechanical presses, such as straight side presses and gap frame presses for stamping and drawing, generally include a frame having a crown and bed and a slide supported within the frame for reciprocating motion toward and away from the bed. The slide is typically driven by a crankshaft having a connecting arm connected to the slide, to which is mounted the upper die. Rotation of the crankshaft moves the connecting rods to effect straight reciprocating motion of the slide. The lower die is conventionally mounted to a bolster which, in turn, is connected to the bed. Such mechanical presses are widely used for blanking and drawing operations and vary substantially in size and available tonnage depending on their intended use.
The primary apparatus for storing mechanical energy in a press is the flywheel. The flywheel and flywheel bearing are normally axially mounted on either the driveshaft, crankshaft, or the press frame by use of a quill. The flywheel is typically mounted at one end of the crankshaft and connected by a belt to the output pulley of a motor such that when the motor is energized, the massive flywheel rotates continuously. The motor replenishes the energy that is lost or transferred from the flywheel during press operations. When the clutch engages the flywheel to transmit rotary motion of the flywheel to the crankshaft, the flywheel drops in speed as the press driven parts are brought up to press running speed.
During clutch engagement, dry and clean clutch linings free from oils or lubricants are necessary to reduce the time necessary to bring the driven parts up to press running speed, and lower times translate to fewer bad parts being produced by the press. Clean, dry brake linings are also necessary for reduced stopping time, and lower stopping times similarly result in fewer unacceptable parts being produced. Also, containing oil or lubricant spillage from leaking flywheel bearings is desirable to keep the local environment clean.
When a flywheel is mounted on a quill journal, seals and various O-rings have typically been placed throughout the quill journal area to reduce the likelihood of oil and lubricant present at the flywheel bearings from migrating to the clutch and brake lining areas. These types of oil control means are passive and work only so long as the seals and O-rings maintain their integrity. External factors such as seal damage due to installation, contamination, corrosion, or seal compression set may degrade the ability of the seals or O-rings to retain oil. Ultimately a leak may occur which wets the clutch or brake linings and thereby results in inefficient operation of the press.
In a variety of sealing devices known in the art, vacuum pressures have been employed to aid in removing oil which has passed by the seals. For example, in a prior art press disclosed in U.S. Pat. No. 5,467,705, a drain port connected to a vacuum source is used to vacuum oil from around a non-rotating, reciprocating shaft that has leaked past a shaft seal.
In particular, vacuuming oil from certain portions of rotating shafts is assisted by the rotation of the shaft. Centrifugal forces associated with shaft rotation tend to fling oil from those shaft surfaces which are axially aligned, and consequently a radially aligned vacuum port may function satisfactorily. However, vacuuming away fluids present on the ends of the shafts, for example on the side of a flywheel, may be complicated if the centrifugal forces tend to throw the fluid past a conventionally mounted vacuum inlet.
Another difficulty with using vacuum pressures to induce an air flow to vacuum fluid off the radially extending surface of a flywheel is that selected clearances should be held to optimize the air flow. Variations in the relative positions of the vacuum housing and flywheel can result in an air flow inadequate to vacuum off the fluid. However, as a slight play in the flywheel mounting may be possible, or the flywheel may be designed to axially shift during its operation, as disclosed in co-pending application Ser. No. 08/537,996, it would be desirable for fluid control systems using vacuum pressures to account for this axial movement.
Thus, it would be desirable to provide a mechanical press having a fluid control system for a rotating component which overcomes the shortcomings described above.